Abstract:

In order to balance wellbore stability and reduce unnecessary waste of resources，based on

the conventional method of delineation of wellbore safety pillar with rock strata movement angle，the engi⁃

neering analogy method is used to optimize the size of wellbore safety pillar in the surrounding rock part of

Grade II rock mass to 80 m，forming a safety pillar with a cylinder at the lower part of the upper platform. At

the same time，the protective mining measures of controlling the exposed area of the stope roof and stratified

filling are taken for the optimized overlying resources around the security pillar. The numerical simulation re⁃

sults show that after mining the surrounding ore body according to the optimized security pillar range，the de⁃

formation of the surface derrick，the winch room and the inner wall of the wellbore does not exceed the maxi⁃

mum allowable deformation value，indicating that the optimization scheme is feasible.

Key words:

rock mass quality classification, safety pillar, shaft, numerical simulation